1. Field of the Invention
This invention relates to printing devices, and more particularly, to printing devices which utilize continuous lengths of paper wound upon a cylindrical roll.
2. Description of the Prior Art
High speed automatic receive-only printers print characters at high rates of speed on a single continuous length of paper which is dispensed from a roll of paper coupled to the printing device itself. These devices are designed to function automatically and do not require the constant attention of an operator. A housing for the printing device typically conceals the roll of paper which the device prints characters on.
Since it is highly undesirable for a printing device of the type described above to continue printing characters after the supply of paper has been exhausted and since it is impossible for an operator to visually ascertain the quantity of paper remaining without removing the cover of the device, it is desirable that the printing device incoporate a system for indicating when a predetermined quantity of paper remains on the roll and when the supply of paper has actually been exhausted.
Since these printing devices also print at extremely high rates which are typically several hundred characters per second, continuous operation of the printing device will rapidly exhaust the paper contained on a single roll. It is therefore advantageous to incorporate a paper dispenser within the printing device with which the rolls of paper are readily removed and replaced with a fresh roll.
Since paper is conveyed by a small electric motor from the roll through the printer, it is desired to minimize the amount of force which must be exerted by the motor on the roll of paper. Doing so not only minimizes the cost of the motor, but also reduces its size permitting the entire printing device to be designed to have a overall smaller physical size.